Why Storage? Part 2: Backup Power & Islanding

by Chris Rigatti

Power outages are surprisingly common for homeowners in the US.

This is especially true in densely populated states like California, Texas and New York.  For instance, California alone had over 400 outages in 2015, and nationwide over 13 million people were affected by blackouts lasting an hour or more.

So what’s to blame? Population growth and an ageing power infrastructure, much of which has been in service since the 1950’s without significant upgrades, are two key factors. However, some of the worst blackouts in recent memory have resulted from severe weather events: “Superstorm” Sandy in 2012, which left over 6 million east coast residents without power for several days, is probably the most well-known example, but each year since then has seen multiple storms causung outages for hundreds of thousands of people at a time. As the climate continues to warm, severe weather events are happening more frequently, and the increased strain on the grid in general means outages are a problem that are not going away in the foreseeable future.

→ Did you miss Part 1? Read the first part of this series here: "Why Storage? Part 1: Solar Self-Consumption." 

Many homeowners installing solar assume that their panels will provide power in the event of a blackout, but the reality is that most residential solar installations are grid-tied only, meaning the panels need a functioning power grid in order to work. It seems counterintuitive, but without an inverter (the part of the system that converts DC power from the solar panels to AC power for loads in the home) capable of “islanding”, or isolating the home from the power grid at large, your solar panels won’t power your home through a blackout.

In addition, solar panels only generate power for 6-8 hours a day in even the sunniest places (Southern California, Hawaii, etc.). So, if you’d like to be protected from outages around the clock, you’ll still need either a generator or…. (you guessed it) batteries!

AquionCharts-backup.pngHow energy storage can keep your power supply continuous during a grid outage. 

While generators have their benefits (mainly cost), batteries have a number of advantages for backup power when coupled with solar panels. First, generators rely on fuel, and in the event of a severe weather event or natural disaster, fuel isn’t always easy to come by. Diesel shortages were common following Hurricane Sandy, for instance. Plus, natural gas lines may be disrupted in the event of an earthquake. If that happens, not even gas-powered generators are guaranteed to work. Second, generators are mechanical systems that require regular maintenance, and since they tend to be used sparingly, you might not find out there’s a problem until you’re already left in the dark.

Aquion’s batteries, on the other hand, are maintenance-free and can be recharged daily from solar so that your home has power even in the event of a power outage that stretches several days.

While it may be cost-prohibitive for some homeowners to install an energy storage system that will power their entire home, it’s common to break out power for a few critical loads (refrigeration, some lights, a few outlets, maybe A/C) and power only those circuits from the solar + battery system in the event of an outage, giving you some calm before, and during, the storm.

Download our Project Spotlight to see how homeowners in Hawaii replaced generators with saltwater batteries for three days of autonomous power: 

hawaii microgrid

Topics: Energy Storage, Residential

Written by
Chris Rigatti
Chris Rigatti is a Product Manager at Aquion Energy. He has over 10 years of experience bringing new technology products to market across a number of industries, including building automation, financial technology, and cloud computing.


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